Bacterial Growth: Page 18/30

Calculate the mean generation time:

The mean generation time or "doubling time" (g) is the average time required for all the components of the culture to double. This is calculated from the following equation:

log₁₀ N_t = log₁₀ N₀ + g log₁₀2

or alternatively:

g = (log₁₀ N_t - log₁₀ N₀) / log₁₀2

Again, for the experiment you have just done:

t₀ = 1.5h:
N = 8.4x10¹,
log₁₀ N = 1.92

t = 8.5h:
N = 3.39x10⁸,
log₁₀ N = 8.53

g = (log₁₀ N_t - log₁₀ N₀) / log₁₀2

= (8.53 - 1.92) / 0.301

= 21.96 generations in 7 hours

= 7 / 21.96 = 0.32 hours (x 60 = 19.2 minutes)

Note that µ and g are related to each other: µ = ln2/g = 0.693/g

Now you try it...